Phytoplankton pigment data collected during the ABRACOS 1 and 2 surveys performed along the northeast Brazilian continental shelf, slope and open ocean

Samples were collected during the “Acoustics along the BRAzilian COaSt (ABRACOS)” oceanographic campaigns, carried out in Austral spring (30 August - 20 September of 2015 - ABRAÇOS1; Bertrand, 2015) and fall (9 April - 9 May of 2017 - ABRAÇOS 2; Bertrand, 2017) on board the French R/V ANTEA. Spring 2015 and fall 2017 are representative of canonical spring and fall conditions in terms of thermohaline structure and currents dynamics (Assunção et al., 2020; Dossa et al., 2021). Water sampling for pigments was carried out using a rosette at four depths defined by CTD profiles: Surface, Mixed Layer, Deep Chlorophyll Maximum (DCM) (which showed a mean depth of 100 m in spring and 80 m in fall) and at 200 m. In shelf shallow stations (< 50 m depth), where no peak of fluorescence was observed, the DCM and 200 m samplings were replaced by a sampling depth at ~10 m above the bottom. For each station and sampled depth, 500 mL of water were filtered in Whatman GF/F glass fiber for the estimation of pigment concentrations of the total phytoplankton community. Size fractionation of water samples was done using 20 μm filter meshes to distinguish the pico- and nanophytoplankton from total phytoplankton pigments. Microphytoplankton fraction (> 20 μm), was estimated by the difference between total and < 20 μm fractions. Filters were stored at 80 ◦C for subsequent HPLC pigment analysis. Chemotaxonomic analysis was carried out on an Agilent Technology 1200 series HPLC following the LOV Method described in Hooker et al. (2000), to assess phytoplankton biomass and diversity. Pigments were extracted in 100% methanol in the dark for 5 min at 4◦C. Samples were then sonicated and filtered on cellulose acetate filters to remove cell debris. A 600 μl aliquot was diluted with 150 μl Milli-Q water. For the analysis, 125 μl of this solution was taken and diluted in an injection loop with 125 μl of a 28 mM solution of Tetrabutyl ammonium acetate. The pigments were then separated on a ZORBAXEclipse XDB-C8 column from Agilent Technology, with 3 mm in diameter,150 mm in length and 3.5 μm in porosity. The column temperature was maintained at 60 ◦C and the flow rate at 0.55 ml min 1. The separation was based on a linear gradient between a solution of methanol/Tetrabutyl ammonium acetate 28 mM, 70:30 (v/v), and a 100% solution of methanol. Chlorophyll-a + Divinyl Chlorophyll-a were used to determine total phytoplankton biomass (TChl-a), while all other pigment markers allowed identifying major algal groups (Table 1). The HPLC system was calibrated with external standards (DHI Water and Environment, Horsholm, Denmark).

样本采集于"巴西海岸声学（ABRACOS）"海洋学考察期间，该考察分别在南半球春季（2015年8月30日-9月20日，ABRAÇOS1；Bertrand，2015）和秋季（2017年4月9日-5月9日，ABRAÇOS2；Bertrand，2017）由法国科考船ANTEA执行。2015年春季和2017年秋季在温盐结构（thermohaline structure）和洋流动力学（currents dynamics）方面代表了典型的春秋季条件（Assunção等，2020；Dossa等，2021）。

使用多瓶采水器（rosette）在CTD（Conductivity, Temperature, Depth）剖面定义的四个深度采集色素水样：表层、混合层、深层叶绿素最大值层（Deep Chlorophyll Maximum, DCM）（春季平均深度100米，秋季80米）和200米层。在深度小于50米的陆架浅水区站位中，若未观测到荧光峰值，则用底部以上约10米处的采样深度替代DCM和200米层采样。

对于每个站位和采样深度，取500毫升水样通过沃特曼GF/F玻璃纤维滤膜过滤，以估算总浮游植物群落的色素浓度。水样的粒径分级通过20微米滤膜进行，以区分微微型和微型浮游植物与总浮游植物色素。大于20微米的微型浮游植物组分通过总组分与小于20微米组分的差值估算。

滤膜保存于80℃以备后续高效液相色谱（High Performance Liquid Chromatography, HPLC）色素分析。采用Agilent Technology 1200系列HPLC，遵循Hooker等（2000）描述的LOV方法进行化学分类分析，以评估浮游植物生物量和多样性。

色素在4℃黑暗条件下用100%甲醇提取5分钟。随后将样品超声处理，并通过醋酸纤维素滤膜过滤以去除细胞碎片。取600微升等分试样与150微升超纯水（Milli-Q）稀释。分析时，取125微升该溶液，在进样环中与125微升28mM四丁基醋酸铵（Tetrabutyl ammonium acetate）溶液稀释。

色素通过Agilent Technology的ZORBAX Eclipse XDB-C8色谱柱分离，该柱直径3毫米、长度150毫米、孔隙度3.5微米。柱温维持在60℃，流速为0.55毫升/分钟。分离基于甲醇/28mM四丁基醋酸铵溶液（体积比70:30）与100%甲醇溶液之间的线性梯度。

叶绿素a+二乙烯基叶绿素a用于测定总浮游植物生物量（总叶绿素a，Total Chlorophyll-a, TChl-a），而其他所有色素标记物可识别主要藻类群（表1）。HPLC系统采用外标校准（丹麦霍斯霍尔姆DHI水与环境公司）。